This invention relates to a projection type display apparatus such as a liquid crystal projector, and more particularly to a technical field relating to a mechanism wherein a projection lens and an exhaust port for radiating heat of an internal heat source therethrough are disposed on a front wall of an outer housing.
Such a liquid crystal projector as shown in FIGS. 15 and 16 which is an example of a projection type display apparatus conventionally is known. Referring to FIGS. 15 and 16, the conventional liquid crystal projector 81 shown includes an outer housing 82 in which an optical unit not shown is built. A projection lens 83 and an exhaust port 84 are provided in a leftwardly and rightwardly juxtaposed relationship on a front wall 82a of the outer housing 82. An exhaust duct 87 having an exhaust fan 86 is disposed between the exhaust port 84 and a light source section 85 which is an internal heat source which generates heat of a high temperature in the optical unit. An image is projected from the projection lens 83 to a projection plane 88 such as a screen, and the exhaust fan 86 is operated so that heat of a high temperature generated by the light source section 85 and heat generated by a power supply section (not shown) and so forth which serve another internal heat source are exhausted in a direction parallel to an optical axis P of the projection lens 83 forwardly of the outer housing 82 from the exhaust port 84 through the exhaust duct 87 by the single exhaust fan 86 thereby to cool the internal heat sources such as the light source section 85 and the power supply section with air.
It is a possible idea to dispose the exhaust port 84 otherwise on a left or right side wall, a rear wall or the like of the outer housing 82. However, since usually a viewer who enjoys an image projected to the projection plane 88 from the projection lens 83 is normally seated around the liquid crystal projector 81 other than the front of the liquid crystal projector 81 outside a projection light flux 89 of the image to be projected to the projection plane 88 from the projection lens 83, a configuration wherein exhaust hot wind 90 of a high temperature generated by the light source section 85 and so forth is exhausted in the forward direction of the outer housing 82 which is the same direction as that of the projection direction of the projection lens 83 from the exhaust port 84 formed in the front wall 82a of the outer housing 82 is most preferable in that the exhaust hot wind 90 of a high temperature exhausted from the exhaust port 84 is not scattered to the viewer to provide a disagreeable feeling to the viewer or blasting sound generated by operation of the exhaust fan 86 is less likely to be offensive to the ear of the viewer.
However, with the system wherein heat generated by the light source section 85, the power supply section and so forth is exhausted from the single exhaust port 84 through the signal exhaust duct 87 using the single exhaust fan 86 as in the conventional liquid crystal projector 81, even if the heat of the light source section 85 can be exhausted comparatively efficiently, heat of such a power supply section as a setting power supply circuit board or a power supply circuit board for a light source section which is normally disposed at a position spaced away from the light source section 85 is cooled only by movement of the air in the inside of the outer housing 82 by operation of the single exhaust fan 86, and the entire cooling efficiency in the liquid crystal projector 81 is low. Therefore, the conventional apparatus has a problem in that it is likely to suffer from deterioration in performance, reduction of the life and so forth because electronic parts such as an IC in the proximity of the power supply section and so forth have a bad influence of heat generated by the power supply section and so forth.
Further, with the structure that the projection lens 83 and the exhaust port 84 are disposed in a leftwardly and rightwardly juxtaposed relationship on the front wall 82a of the outer housing 82 as in the conventional liquid crystal projector 81 described above, since the optical unit in the outer housing 82 and the projection lens 83 are offset to one side with respect to the center of the outer housing 82 in the leftward and rightward widthwise direction, the liquid crystal projector 81 suffers from an imbalance in weight in a leftward and rightward widthwise direction. Therefore, as shown in FIG. 17, when the liquid crystal projector 81 is suspended on a ceiling in a room etc. by means of hanger elements 94, the liquid crystal projector 81 is likely to be inclined in the leftward and rightward widthwise direction. Further, when an operator holds the liquid crystal projector 81 high above the head with both hands to perform an attaching operation of the liquid crystal projector 81 to the ceiling in order to hang the liquid crystal projector 81 on the ceiling, the liquid crystal projector 81 cannot be balanced readily in the leftward and rightward direction, and the attaching operation cannot be performed readily, or the balance may be lost, resulting in a falling or dropping accident of the liquid crystal projector 81. Further, when the liquid crystal projector 81 is hung on the ceiling 93 in a room or the like by the hanger elements 94, although generally an operator holds the liquid crystal projector 81 high above the head with both hands to set the projection lens 83 to a central position of the projection plane 88 such as a screen hung on a wall or the like, if the projection lens 83 is offset to one side of the outer housing 82, then since the projection lens 83 is displaced to one side from the position of the head of the operator, the projection lens 83 cannot be positioned at the center of the projection plane 88 with reference to the position of the head of the operator. Therefore, the operability is very low.
Further, in the system wherein, during projection of an image to the projection plane 88 such as a screen by the projection lens 83, the exhaust hot wind 90 of a high temperature generated from the light source section 85, the power supply section and so forth is exhausted in a direction parallel to the optical axis P of the projection lens 83 forwardly of the outer housing 82 which is the same direction as that of the projection light flux 89 by the projection lens 83 as in the conventional liquid crystal projector 81, particularly where a short focal length lens having a short focal length is used for the projection lens 83 and the projection angle (angle of view) xcex8 of the projection light flux 89 is great, part of the exhaust hot wind 90 is liable to advance into part of the projection light flux 89.
Then, if the exhaust hot wind 90 advances into the projection light flux 89, then there is the possibility that a non-uniform air density region 91 wherein the refraction index of the air in the projection light flux 89 varies locally may be produced in the portion into which the exhaust hot wind 90 advances and a schlieren 92 by which such picture quality deterioration as fluctuation or distortion of an image projected to the projection plane 88 through within the non-uniform air density region 91 occurs with the image may possibly occur.
It is an object of the present invention to provide a projection type display apparatus wherein heat generated from a plurality of heat sources in the inside of an outer housing can be exhausted efficiently and the weight of the outer housing can be balanced readily in the leftward and rightward direction.
It is another object of the present invention to provide a projection type display apparatus wherein a projection lens and an exhaust port for an internal heat source are disposed on a front wall of an outer housing to assure a good convenience of use and occurrence of a schlieren of a projected flux of light by hot wind of exhaust air can be prevented.
In order to attain the objects described above, according to an aspect of the present invention, there is provided a projection type display apparatus, including an outer housing, first and second internal heat sources accommodated in the outer housing and operable to generate heat at different temperatures from each other, and first and second exhaust mechanisms including first and second exhaust fans for cooling the first and second internal heat sources independently of each other with air, respectively.
In the projection type display apparatus, hot air generated at the two locations by the first and second internal heat sources such as a light source section and a power supply section in the outer housing can be exhausted independently of each other without being thermally influenced by each other by the first and second exhaust mechanisms having the first and second exhaust fans, respectively. Consequently, the first and second internal heat sources in the outer housing can be individually cooled with air, and the entire inside of the outer housing can be cooled with a very high air-cooling efficiency. In particular, the exhaust mechanism for cooling a power supply section with air can cool electronic parts of the power supply section with air without being influenced by a light source section which acts as an internal heat source which exhibits a higher temperature than the power supply section. Consequently, deterioration in performance, reduction in life and so forth of the electronic parts of the circuits including the power supply section by a bad influence of heat can be prevented to the utmost. Accordingly, the projection type display apparatus is high in performance and long in durability.
The projection type display apparatus may further include a power supply section for supplying power for driving the projection type display apparatus, an optical unit including a light source section and a light valve for modulating light emitted from the light source section, and a projection lens for projecting the light modulated by the light valve to a screen, the first internal heat source being the light source section of the optical unit while the second internal heat source is the power supply section.
Preferably, the projection lens is disposed at a substantially central portion of a front wall of the outer housing, and first and second exhaust ports of the first and second exhaust mechanisms are disposed on the opposite sides of the projection lens in the front wall of the outer housing.
Since the first and second exhaust ports of the first and second exhaust mechanisms are disposed on the opposite sides of the projection lens in the front wall of the outer housing, the projection lens and the optical unit for color separation and color synthesis which have weight in a high ratio in the entire projection type display apparatus and positioned at the central position of the outer housing. Consequently, the entire projection type display apparatus can be balanced in weight readily and therefore can be hung stably on a ceiling or the like of a house. Further, since the exhausting directions of hot wind to be exhausted from the first and second exhaust ports can be set to the same direction as the projection direction of an image to a projection plane such as a screen by the projection lens, exhaust hot wind of a high temperature is not scattered to a viewer to provide a disagreeable feeling to the viewer or blasting sound generated by operation of the first and second exhaust fans is less likely to be offensive to the ear of the viewer. Therefore, the projection type display apparatus can be used in good convenience. Further, when an operator tries to hold the projection type display apparatus high above the head with both hands to attach the projection type display apparatus to a ceiling of a house, the projection type display apparatus can be balanced readily in weight. Furthermore, when the operator holds the projection type display apparatus high above the head with both hands, the projection lens can be positioned naturally above the head, and therefore, the operator can position the projection lens at the center of the projection plane with reference to the position of the head of the operator itself. Consequently, the attaching operation of the projection type display apparatus to a ceiling can be performed readily.
The projection type display apparatus may further include a first exhaust duct for interconnecting the first internal heat source and the first exhaust port, and a second exhaust duct for interconnecting the second internal heat source and the second exhaust port. With the projection type display apparatus, heat generated by the first and second internal heat sources can be exhausted efficiently as hot wind from the first and second exhaust ports through the first and second exhaust ducts.
Preferably, a duct wall of at least one of the first and second exhaust ducts is formed from part of the outer housing. This simplifies the structure and production of the projection type display apparatus. Thus, the production cost of the projection type display apparatus can be reduced by reduction of the number of parts and the number of assembly steps.
Preferably, the optical unit is disposed at a substantially central position in the outer housing, and the first exhaust duct is connected between the light source section of the optical unit and the first exhaust port which is disposed on one side of the front wall of the outer housing while the second exhaust duct is connected between the power supply section of the optical unit and the second exhaust port which is disposed on the other side of the front wall of the outer housing. This facilitates balancing in weight of the projection type display apparatus.
Preferably, the power supply section includes a setting power supply circuit board and a light source power supply circuit board, and the second exhaust duct has the duct wall formed from the outer housing in a substantially J- or L-shape along a side face portion to a rear face portion of the optical unit while the setting power supply circuit board and the light source power supply circuit board are disposed in the second exhaust duct. In the projection type display apparatus, the second exhaust duct can be formed with a great volume, and a plurality of power supply sections such as the setting power supply circuit board and the light source section power supply circuit board can be disposed readily in the inside of the second exhaust duct and can be cooled efficiently with air.
Preferably, intake ports for the first and second exhaust ducts are formed in the outer housing. In the projection type display apparatus, external cooling air can be sucked into the first and second exhaust ducts through the intake ports and used to compulsorily cool the first and second internal head sources efficiently with air.
Where the optical unit includes color separation means for separating the light emitted from the light source section into light components of different colors such that the light components of different colors may be inputted to a plurality of light valves provided in the optical unit and color synthesis means for synthesizing the light components from the light valves so that the synthesized light components are emitted from the projection lens, preferably the projection type display apparatus further includes an intake fan and an intake duct disposed on a bottom portion of the outer housing for compulsorily taking in air to the light source section and an image synthesis section formed from the light valves and the color synthesis section. In the projection type display apparatus, the image synthesis section and the light source section of optical unit can be compulsorily cooled efficiently with air by a synergetic effect of a compulsory intake action to the image synthesis section and the light source section by the intake mechanism including the intake fan and the intake duct disposed on a bottom portion of the outer housing and a compulsory exhaust action by the first exhaust mechanism.
According to another aspect of the present invention, there is provided a projection type display apparatus, including an outer housing, first and second internal heat sources accommodated in the outer housing and operable to generate heat at different temperatures from each other, first and second exhaust mechanisms including first and second exhaust fans for cooling the first and second internal heat sources independently of each other with air, respectively, a projection lens provided on a front wall of the outer housing, the outer housing having, in the front wall thereof, an exhaust port for radiating heat of the first and/or second internal heat sources, and wind guiding means for guiding hot wind exhausted from the exhaust port so that the hot wind may not advance into a projection light flux of an image to be projected from the projection lens.
In the projection type image display apparatus, although the projection lens and the exhaust port or ports for the internal heat sources are disposed on the front wall of the outer housing and hot air of heat generated by the internal heat sources is exhausted in the forwardly direction of the outer housing same as the projection direction by the projection lens, the hot wind exhausted from the exhaust port or ports can be guided so that it does not advance into a projection light flux of an image to be projected by the projection lens. Consequently, even where a short focal length lens is used as the projection lens and the angle of view of the projection light flux to be projected to the projection plane such as a screen is great, such a situation that part of the hot wind exhausted from the exhaust port or ports advances into the projection light flux to cause picture quality deterioration such as fluctuation or distortion of an image by a schlieren can be prevented. Consequently, the projection type image display apparatus can normally project an image of high quality.
Where the projection type image display apparatus further include an exhaust duct disposed between the internal heat source and the exhaust port, preferably the wind guiding means may include baffles provided in the inside of an end portion of the exhaust duct adjacent the exhaust port. Or else, the wind guiding means may include an exhaust fan disposed on the inner side of the exhaust port or baffles provided in the exhaust port. In the projection type image display apparatus, provision of a special mechanism for preventing a schlieren can be eliminated. Consequently, the projection type image display apparatus is simplified in structure and production and can be produced at a reduced cost.
Preferably, an inclination direction of the baffles is adjustable. In the projection type display apparatus, the exhausting direction of hot wind to be exhausted from the exhaust port or ports can be adjusted freely in accordance with the focal length of the projection lens. Consequently, prevention of a schlieren can be realized with a higher degree of certainty.
These and other objects and features of the present invention will become clear from the following description of the preferred embodiment given with reference to the accompanying drawings in which like parts or elements are denoted by like reference symbols.